American History X is a good choice. Great movie, but disturbing. One of the few I still find disturbing as a grown man. Serpico is up there for completely different reasons. I've always been disturbed at the gang mentality of cops, and that an honest cop couldn't be trusted purely because he was honest, and eventually was nearly killed. There are scenes in some gangster movies I still find pretty disturbing such as how Joe Pesci is killed at the end of Casino.

As far as horror, well, the original Texas Chainsaw massacre was pretty twisted to me, and made me feel uneasy when I was younger, same with the original Halloween and the Exorcist(I saw it when I was very young, and was initially raised Catholic....not strict Catholic, but I did at that age assume that sort of thing was real)

Tightrope with Clint Eastwood was actually a pretty weird movie to watch as a kid.

Edit: I watched the remake of The Thing with Kurt Russell when I was 4-5 years old with my father, and that scared me quite a bit at the time, particularly the ending.

Horror movies haven't scared me or disturbed me since I was very young, though I still enjoy them.

Serpico is up there for completely different reasons. I've always been disturbed at the gang mentality of cops, and that an honest cop couldn't be trusted purely because he was honest, and eventually was nearly killed.

I live very close to that building where Serpico got shot. I was talking with a guy at a bar once and we were talking about NYC movies and I mentioned that and this other guy three stools down turns around and mentions he lives in that people and his roommate became kind of obsessed with that fact. He said he eventually ended up having a phone call with Serpico from Switzerland, I think.

The Mail and Express reported appointment as a patrolman cost $300, promotion to sergeant, $1,400, and advancement to captain, $14,000. Policemen made back their investments by taking bribes.

If you want to know more about the Serpico days, I recommend two books.This one is about David Durk. He was the guy Tony Roberts played in the movie and he was much more important to the case than the movie makes out. This one examines crime in New York in 60's through three people, one a innocent black guy framed by the cops, another who is a gang member who joins and eventually gets into a war with The Black Panthers and the third is a thoroughly corrupt cop who joined the force to steal and was eventually the big witness in Knapp Commission hearings. He was a more imporant witness than Serpico, because cops wouldn't keep things from him, since he was dirty himself. Here's a clip of him testifying before the Knapp Commission. Check out how the old-school pixelation technology! Black marker, baby!